光伏发电功率持续时间特性的概率分布定量分析

Quantitative Analysis of Probability Distribution for Duration Time Characteristic of Photovoltaic Power

随着光伏发电渗透率在电力系统中的快速增加,电网的规划和调度过程中均有必要对其进行精细化的考虑。但光伏发电功率具有较强的随机性,对其稳态功率特性的描述需要采用概率统计手段。首先根据光伏出力运行点及其波动限值定义了光伏出力状态,然后针对光伏出力维持在某一状态不变的时间长度进行了定量研究,提出了光伏发电功率持续时间分布的概念。基于德国和中国实测数据的分析表明:光伏出力的持续时间分布存在明显的双峰值特征,适合采用逆高斯分布和广义极值分布函数进行加权混合拟合;双峰值特征表明,光伏发电可能在局部云层扰动下出现快速功率波动,从而只能在数分钟内保持出力状态不变,也可能在天气条件良好时跟随日地运动缓慢变化,其出力可维持某一状态长达数小时。所述研究可用于光伏发电功率调度控制过程中测量和决策周期的选定、光伏电站输出波动限值检验等,进而为输电系统中设备的设计选型提供重要的参考依据。

With the rapid increase of the photovoltaic（PV）power penetration,it is essential to precisely consider the impacts of PV power on power system planning and operation.However,due to the uncertainty and volatility of PV generation,statistical approaches are required to describe its features.This paper quantitatively depicts the distribution of the time for PV power to continuously maintain a certain output status.Firstly,the output status of PV power is defined by the operation point and deviation range of PV power,then the duration time characteristic is proposed.It is indicated by numerical results based on field measured data of China and Germany that：there is an obvious ＇ double peaks property ＇ in PV power duration time distributions and it can be properly fitted by the mixture of inverse Gaussian and generalized extreme value probability density function.The ＇ double peaks property ＇ further reveals that under frequent disturbances of clouds,PV power will maintain the current output status for only a few minutes.Otherwise,PV generation can smoothly follow the regular changes of solar radiation and keep the current output status unchanged for hours.Research results of this paper can provide important references for the optimal choice of the measurement and control time interval in the PV generation dispatch,validation of the maximum output variability,and for design and selection of power equipment in transmission systems.